1. Field
The embodiment relates to a wireless power transmission technique.
2. Background
A wireless power transmission or a wireless energy transfer refers to a technology of wirelessly transferring electric energy to desired devices. In the 1800's, an electric motor or a transformer employing the principle of electromagnetic induction has been extensively used and then a method for transmitting electrical energy by irradiating electromagnetic waves, such as radio waves or lasers, has been suggested. Actually, electrical toothbrushes or electrical razors, which are frequently used in daily life, are charged based on the principle of electromagnetic induction. The electromagnetic induction refers to a phenomenon in which voltage is induced so that current flows when a magnetic field is varied around a conductor. Although the commercialization of the electromagnetic induction technology has been rapidly progressed around small-size devices, the power transmission distance is short.
Until now, wireless energy transmission schemes include a remote telecommunication technology based on resonance and a short wave radio frequency in addition to the electromagnetic induction.
Recently, among wireless power transmission technologies, an energy transmitting scheme employing resonance has been widely used.
In a wireless power transmission system employing resonance, since power is transferred through coils of the wireless power transmitter and the wireless power receiver is wirelessly transferred through coils, a user may easily charge electronic appliances such as a portable device.
The wireless power receiver is provided with a magnet such that the wireless power transmitter senses the wireless power receiver. The wireless power transmitter senses a magnetic field by the magnet of the wireless power receiver and determines whether to charge the wireless power receiver.
However, in the related art, the magnet of a wireless power receiver has been formed of rare earth elements and the rare-earth magnet is very expensive, so that the cost of manufacturing the wireless power receiver is increased.
In addition, the magnet of a wireless power receiver according to the related art does not meet the arrangement requirements required by the standard.